Analog Devices Inc. HMC684LP4ETR

Overview

HMC684LP4ETR from Analog Devices (formerly Hittite Microwave) is a BiCMOS MMIC double-balanced mixer with integrated LO amplifier, designed for RF-to-IF downconversion and upconversion in 700–1000 MHz systems. It delivers 7 dB typical conversion loss, +32 dBm input IP3, and +25 dBm input P1dB at 0 dBm LO drive, supporting cellular infrastructure transceivers requiring high linearity and wide IF bandwidth (DC–450 MHz).

For engineers reviewing the HMC684LP4ETR datasheet, HMC684LP4ETR pinout, HMC684LP4ETR application, or HMC684LP4ETR equivalent, key selection criteria include its integrated LO amplifier enabling low-LO-drive operation (–6 to +3 dBm), 24-pin 4×4 mm QFN package with exposed paddle, and verified performance across –40°C to +85°C for base station repeaters and LTE/WiMAX front-ends.

Technical Context

The HMC684LP4ETR implements a passive double-balanced mixer core with on-die LO buffer amplifier, enabling single-ended 50 Ω RF and LO ports matched via internal baluns. Its differential IF interface (IFP/IFN) supports DC-coupled or AC-coupled operation up to 450 MHz, while internal bias networks allow flexible external control of LO buffer current (via LO_BIAS) and optional G_BIAS.

It operates over full industrial temperature range (–40°C to +85°C) with total supply current of 85–100 mA across Vcc1/Vcc2/Vcc3 at +5 V, and features robust isolation: ≥23 dB LO-to-RF, ≥30 dB LO-to-IF, and ≥35 dB RF-to-IF - critical for suppressing spurious mixing products in dense RF environments.

Key Specifications

Pinout & Package

Package: 24-lead, 4 mm × 4 mm, 0.85 mm height QFN with exposed thermal paddle (RoHS-compliant matte tin finish, MSL1, peak reflow 260 °C). Ground paddle must be soldered to PCB RF ground plane using ≥9 thermal vias.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF mixer applications.

Compared with HMC684LP4ETR, HMC685LP4ETR offers identical mechanical and electrical interface but shifts frequency coverage upward, while ADL5801ACPZ-R7 trades passive linearity for active gain and wider bandwidth - making HMC684LP4ETR optimal for fixed-band, high-dynamic-range infrastructure applications.

Availability

HMC684LP4ETR is available at Aetrix Electronics and suitable for cellular base stations, LTE small cells, and WiMAX repeaters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for HMC684LP4ETR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices acquired Hittite Microwave in 2014 and maintains its high-frequency RF portfolio, delivering precision RF, microwave, and millimeter-wave components for communications, defense, and instrumentation.

The HMC684LP4ETR belongs to Hittite's legacy BiCMOS MMIC mixer family, engineered specifically for high-linearity, low-LO-drive infrastructure applications in licensed wireless bands below 1 GHz.

FAQ

What is the operating temperature range for the HMC684LP4ETR?

The HMC684LP4ETR is specified for continuous operation from –40°C to +85°C ambient temperature, with guaranteed performance across this range for RF parameters including conversion loss, IP3, and isolation. Its thermal resistance (channel-to-ground paddle) is 58 °C/W, enabling reliable operation at full 0.69 W dissipation when mounted on a properly designed PCB with thermal vias.

Does the HMC684LP4ETR require external DC blocking capacitors on the RF or LO ports?

No - the HMC684LP4ETR integrates baluns that DC-short the RF and LO ports internally, so external DC blocking capacitors are not required on pins 3 (RF) or 16 (LO). However, DC blocking is recommended on the differential IF pins (21, 22) if the application does not require DC-coupled IF operation, as stated in the datasheet.

How is the LO drive level controlled in the HMC684LP4ETR?

The LO drive level in the HMC684LP4ETR is adjusted via the LO_BIAS pin (pin 9), which controls current in the integrated LO amplifier using an external resistor. The datasheet provides bias network examples to set LO output power between –6 and +3 dBm, allowing optimization of conversion loss versus linearity for specific system requirements.

Is the HMC684LP4ETR suitable for upconversion applications?

Yes - the HMC684LP4ETR supports both upconversion and downconversion. Its balanced architecture and wide IF bandwidth (DC–450 MHz) enable clean synthesis of 700–1000 MHz RF signals from baseband I/Q inputs, as confirmed by measured upconverter performance plots in the datasheet showing conversion gain and IP3 vs. LO drive.

What is the meaning of "pin-for-pin compatible with HMC685LP4ETR" for the HMC684LP4ETR?

This means the HMC684LP4ETR and HMC685LP4ETR share identical 24-pin QFN footprints, pin numbering, supply configurations (Vcc1/Vcc2/Vcc3), bias interfaces (LO_BIAS, G_BIAS), and RF/IF/LO port assignments - enabling direct substitution on the same PCB layout when changing frequency bands from 700–1000 MHz to 1.7–2.2 GHz without redesign.